Many data communication systems, such as process control systems, require the display on a single display device of data from multiple processors. An example of a process control system having multiple processors is a binding line for binding books, magazines, and the like. A binding line typically includes a line controller for controlling a plurality of packer boxes for feeding signatures to a gathering conveyor, a binder for binding the signatures together, a trimmer for trimming excess paper off the bound signatures, and the like. An auxiliary controller, which communicates with the line controller, transmits and receives certain information to and from the line controller of the binding line. The auxiliary controller may be arranged to control all equipment on the binding line not controlled by the line controller.
It is often advantageous to display messages to the operators of binding lines in order to help these operators perform their duties efficiently. When the line controller provides messages according to a first message protocol and the auxiliary controller provides messages according to a second, different message protocol, a first display controller capable of managing messages according to the first message protocol may be provided in order to display the messages from the line controller on a display device, and a second display controller capable of managing messages according to the second message protocol may be provided in order to display the messages from the auxiliary controller on the same display device.
However, the use of multiple display controllers adds unnecessary complexity and cost to a process control system such as a binding line or a binding line system. The present invention is directed to a single display controller that is capable of responding to different message protocols from multiple message sources in order to provide display on a single display device of messages having a common format.